Engine-cylinder-scavenging mechanism



H. A. GEHRES ENGINE CYLINDER soAvENGING MECHANISM A Filed March 17. 1924 @Sheets-Sheet 1 1,644,777 oct. 11,1921. y H. A GEHRES ENGINE, CYLINDER SCAVENGrINGr MECHANISM Filed March 17, 1924 5 Sheets-Sheet 2 C) G O C) GJ l v l l) 10 Q J0 8 I IZ J2 it 311 6 31 11 /v/' J3 I3 J5 J5 4 v 4 y I y 'l vwamtoz Wwf. WM

' 1644777 11'1927" H. A.GEHREs 'y ENGINE CYLINDER CAVENGING MECHANIS-M Fileduaron 17, 1924 5 sheetsfsneet 3 1 rk J4" 4 5 7 l Scavengmg Air' l [xH/1037 1001974954 Z1 uvemtoz ,wz/a4 gjm Fatented et. ll, i927. i i

HEWETT A. 'GHRE 0F MOUNT VERNON, OHIO.

ENGINE-CYLINDER-SCAVENGNG MECHANISM.

Application led March 17, 1924. Serial No. 699,693.

The invention relates to a scavenging Fig. l6 is a view similar to Fig. l, but mechanism for internal combustion engines, showing amodiied form of the invention. Y` more especially of the two-cycle type. One j Fig. 7 is a graphic chart showing thevalve feature of the invention relates to the proand port 'openings of the scavenging mechavisionof a port at one end of the cylinder nism as shown in Figs. lAto 6. 60

for directing a stream of scavenging air ln Fig. 1 l have/shown an internal coinlongitudinally therethrough. The valve for bustion two-cycle engine cylinder 1 which controlling a port of the above nature usumay be, for example, of the `Diesel type, ally must be of large size in order to afford and having a piston 2 which uncovers an eX- ]o adequate area of opening, and it is desirable haust port 3 toward the 'end of its power 65 to' employ a valve which will openquickly stroke. Certain component parts of-the enl in order to provide unimpeded flow of the gine will not be described herein, since the scavenging air at all times when the valve is lpresent invention is not particularly conopen. However, it is difficult to provide a cerned with them.

valve which will satisfy both ofthe above ln accordance withathe present invention 70 requirements, since if a large valve is acl provide in or adjacent the cylinder-head celerated when opening and closing, encesI 4, a scavenging port 5 through which the sive noise is created due to slamming against air to be employed for scavenging purposes the valve seat, and, on the other hand, fif is led in any suitable manner, as by a pasthe valve opens and closes slowly, its area sageway 6 in the cylinder head. A valve 7Y 75 of opening at these times is unduly small. controls communication between the port 5 One object of the present invention is t0 and the cylinder head, the illustrated valve provide a scavenging valve which will have being of the poppet type, and having a valve adequate area lof opening at all times, and stem 8 actuated to open and close valve 7 at avoid mechanical difficulties such as are the proper times. In the present instance 80 above mentioned. I the valve is actuated by a rocker arm 9 piv- Another object of the invention is to imoted to a bracket 10 extending from the prove the scavenging action by combining' cylinder head 4, the arm 9` beingk moved with a valve of the above character, a scavback and forth in timed relation to the Anioenging port located adjacent the opposite tion ofthe piston, to open and close valve 7 85 end.V of the cylinder and near the exhaust at the proper times. `To avoid undue noise port thereof, in such manner as to secure in the operation of valve 7 it is preferably the combined effect of a stream of scaveng-` moved slowly in opening land closing, but ing air traveling longitudinally through the may bev moved relatively quickly in intercylinder and a local transverse stream of air mediate positions. This motion may be im- 90 near the exhaust port, to 'the end that all pai-ted by any suitable valve gear; in Fig. 2, parts of the cylinder may be thoroughly for example, I have shown conventionally scavenged. crank 9a, which is connected to the arm 9 by Other objects and advantages of the ina link 9", to typify the motion of the 10 vention will be in part obvious and in part valve. 95

specifically pointed out in the description An auxiliary valve 11 is interposed behereinafter contained, which, taken in con- .tween the port 5 andthe passageway 6, in nection with the accompanying drawings, such manner that the 4scavenging air does discloses certain preferred embodiments not necessarily flow into the cylinder at all thereof; such embodiments, however, are to times .when valve 7 is open, and the auxillo@ i be considered merely as illustrative of its lary valve 11 is arranged to open somewhat principles. In the drawings: later than valve 7. In the form of the 1n- 'Fig 1 is a central longitudinal section of vention illustrated in Fig. 1, the auxiliary an engine cylinder equipped with a scaveng' p valve ll 1s of the'piston type and slides 0 ing mechanism operating in accordance with. within a sleeve- 12 interposed between port 105 the invention. j 5 and passageway 6, but provided with Figs. 2 to 5 vare views similar to Fig. 1, openings 13 which are uncovered sin. certain showing the scavenging mechanism in difpositions of valve l1. The valve 1l is shown ferent positions which it assumes during as txedly carried by stem 8 of valve 7` and the cycle of the engine. as valve 7 moves to full open position, the 110 valve 11 will move downward sufficiently to uncover the openings 13 in sleeve 12, and holes 14 in the valve will uncoverthe lower openings 18 in such sleeve.

Accordingly, in the operation of the engine, the valve 7` may be partially opened,

prior to the time when it is desired to have scavengin air enter the cylinder; and valve 11 Awill e opened at just the time the scavenging air is desired. lVhen the auxiliary valve 11 opens, valve 7 will already have moved away from port sulliciently to afford a large opening in such port through which the scavenging air may pass;

* and as above stated the motion of valve 7 may be accelerated as it moves away from port 5, to the end that valve 11 will open rapdlyand at once admit a full volume of j above described the valve 7 may be opened and closed so slowly as to permit smooth quiet operation', and yet admission'and cut" olf ofthe scavenging 'air will be brought l about quickly and without undue restriction inthe areas of valve opening afforded. Unless an auxiliary valve be employed as above described, an opening motion of the valve 7 slow enough to avoid excessive noise,- andl other mechanical diliieulties,'will unduly re-` l strict the area of the valve opening afforded in the initial stages of movingl the valve toi *onfrom its valve seat.

Preferably the cylinder .is also provided with a scavenging port 15 located in th'e region of` exhaust lport 3, and directing a stream of air transversely across' the head of piston 2 to the exhaust port. Thus the cylinder is scavenged by the combined action ofthe stream of-air passing longitudinally through'the cylinder from port 5, and a further stream of air which entere through port 15 and sweeps directly across [over the head of the piston and into the exhaust poit. The longitudinal stream offair above mentioned .niodiiies the transverse-l streani in such a way'as toguide the latter; h

'point 19, at which latter point the port 15 into a "transverse path ot.. movement across the portion'of the cylinder in Ewhich the longitudinal streamI is least effective. The transverse stream of air taccordingly does not pass upwardly to the top' of thecylin# der and then have to'reverse itselil in pass ing tothe exhaust port 3,as other-wise would be the ease. f

Leser?? Although the scavenging port 15 is preferably employed, it will be understood that it maybe dispensed with, and the longitudinal stream of airy issuing through port 5 alone depended on for scavenging.

In the position of parts as shown in Fig. 1, the piston -2 is approaching the end of its power stroke, and has just uncovered exhaust port 3. Valve 7 has moved to partially open position, but no scavenging air has yet entered the cylinder since auxiliary Valve 11 is still closed, and the piston has not yet uncovered port 15.

As shdwnin Fig. 2, the piston has moved downwardly to dead centre upon completion of its power stroke; .valve 7 has moved to full open position and valvell has also opened, thus admitting the longitudinal stream of air above described. The piston haslalso uncovered port 15, thus admitting the transverse stream of scavenging air.

In Fig. 3 thepiston has moved upwardly a suiticient distance to cover port 15, but valve 7 and also auxiliary valve 11 are still open, permitting the longitudinal stream 'ot scavenging air to still pass through the cylinder and out through exhaust port 3.'

According to Fig. 4 the piston has moved up still further to close' exhaust port 3, but air is st illpermittedto enter the cylinder, since valve 7 is stillopen, and theauxiliary valve y11 is only just beginning to close.'

The yscavenging lmechanism Ithus permits supercharging of the cylinder to take place.` Fig. 5 shows `the piston 2 still further advanced upon its compression stroke, the valve 7 being still partially open, but valve 11 beingy closed, whereby the supply ot' scavenging air is cut ofi. f

F ig. 7 shows diagrammatically the condition of the various port openings at various times in 4the cycle ot the engine when the valves or ports are open. the 'valve' andl port openings being plotted Aagainst time. Point 16 at the lett of the ligure shows zero openings for all the ports, and exhaust port 3 and valve 7 are just beginning to open;

The areal of the exhaust port is indicated in the diagram by the abscissal oi' the larger triangle having the criss cross lines at its sides. The amount of opening of valve 7 is shown by thev points on line 17. At the point 18"val vc 11 opens and also pist-on 2 begins to uncover port 15, and the area of opening of port l5 is indicated by the vertical lines in the smaller central triangle ot Fig. 7 between the point 18 and the is again closed. The combined scavengingT port area is denoted by the total length of the vertical sectional lines in Fig. 7, and exhaust continues until the point 20 is reached, when the exhaust port 3 closes. The valve 11, however, remains open a furth'er period until the point 21 is reached, and

llOv

recevra' l the cylinder pressure. This valve may be,

for example, what is known in the art as a plate valve, whichwll 'open .automatically een opened land the exliaistt'pn' proceeded sufficiently to reduce the pressure in the cylinder to a value below that at` which the scavenging air'in chamber 23'is supplied. The valve 11a will then remain open until piston 2 has proceeded arenough in its compression stroke to build up a supercharging pressure in the cylinder,` greater than that in scavenging air chamber 23.

i opening of While' certain embodiments of the invention have been described, it will be obvious that many changes may be made therein without departing from its principles, as delined in the following claims. v

I claim:

1. A cylinder scavenging mechanism com-` prising a scavenging port at the head of the cylinder, a valve therefor, and an auxiliary valve controlling communication to sai port, said .auxiliary valve being timed to remain closed during the ',initialstage of opening of said first mentioned valve and then open toV admit scavenging air through said port to the cylinder.

v2. A cylinder scavenging mechanism coinprising a scavenging port at the head of the and an auxiliary p cylinder, a valve therefor, valve controllingv communication,l to said port, said auxiliary valve being timed to remain closed during the initial stage of open. ing of said first mentioned valve and then open to admit scavenging air through said port to the cylinder, said auxiliary valve also closing earlier than said irst mentioned valve.

3.' A cylinder scavenging mechanism` comprising a scavenging port at the head of the cylinder, a valve adapted to seat against the walls of said port, actuating means for said valve adapted to move the same relatively slowly when near the walls of the port, and more rapidly in intermediate positions, Dan auxiliary valve controlling communication to said port, said auxiliary valve being timed to remain closed during the initial stage of said first mentioned valve, and then open to admit scavenging air through said port to the cylinder: y

4. A cylinder scavenging mechanism coniprisingV a scavenging port at the head ofmthe cylinder, a valve adapted to seat againstthe walls of said port, actuating means for said valve adapted to move the same relatively slowly when near the walls of the port, and more rapidly in intermediate positions, an

auxiliary valve controlling communication to mOVe tioned valve is being moved relatively rap.-

Cport, said auxiliary valve being ralso bysaid actuating means and timed to f open the auxiliary-valve'when the r'st men'fy idly, to admit scavenging air through said" port to the cylinder.

5. A cylinder scavenging mechanism conivprising a scavenging port atthe head of the' cylinder, a poppet valve orsaid port, van auxiliary valve of the piston type control'- ling communication toi said port, and connected to the stemof said poppet valve, said piston valve beingxtimed to" remain closed during the initial stagev of opening of said poppet valve and then open to admit scavenging air throughsaid poppet valve to the cylinder.

6.V A cylinder scavenging mechanism comprising a scavenging port located near the iead end of the c linder and. positionedy to direct a stream of scavenging airlongitudinally through the cylinder,-a valvefor said port, an auxiliaryI valve controlling communication to said port,`said auxiliary valve d air through said port to the cylinder, an exhaust port located near the opposite end of the cylinder and -a further scavenging port located in the region of the exhaust port and admitting atransverse stream of scavenging y air across they cylinder to the exhaust port, when the latter is open. v

-7. A cylinder scavenging mechanism com-4 rising a scavenging port located near the head end of the cylinder, a valve therefor, an auxiliary valve controlling communication to vsai valve whereby scavengin air may pass into the cylinder only when oth of said ports are open, said auxiliary valve being timed to close prior to said lirst mentioned valve.

8. A cylinder scavenging mechanism comA prising a scavenging port located near the head end of the cylinder, a valve therefor, an auxiliary valve controlling communication to said port whereby scavenging air may pass into the cylinder only when both of said valves are open, an exhaust port in said cyl-l inder, said valves both being timed to remain open after the exhaust port has. closed, and said auxiliary valve closing prior to said first mentioned valve;

In testimony thatI claim the foregoing, I

have hereunto set my hand this 15th day of February, 1924.

HEWETT A. GEI-IRES.` 

